This invention relates to a novel magnesium-containing solid which is useful as a carrier for various kinds of catalysts, particularly a catalyst for polymerization of ethylene and alpha-olefins (hereinafter referred to simply as the olefins). More particularly, it is concerned with a novel magnesium-containing solid which is useful as a carrier for the Ziegler catalyst for polymerization of olefins, and a component of an olefin polymerization catalyst comprising such a solid, particularly in the form of uniform particles.
Various kinds of substances have hitherto been proposed for use as the carrier for a Ziegler catalyst for polymerization of olefins. A solid containing magnesium is useful as a catalyst for polymerization of olefins, and particularly as a carrier for any such catalyst. Various methods have been proposed for obtaining uniform particles of a solid containing magnesium.
For example, it has been proposed to obtain spherical particles by spraying an aqueous solution of magnesium chloride, or molten MgCl.sub.2.6H.sub.2 O as disclosed in U.S. Pat. Nos. 3,953,414, 4,111,835 and British Pat. No. 2,006,227, or obtain appropriate particles by classifying particles of magnesium chloride powder as disclosed in Japanese Patent Application Laid-Open No. 127185/76.
For manufacturing a solid containing magnesium, it has, for example, been proposed to contact metallic magnesium, a halogenated hydrocarbon and an electron donative compound such as alcohol as disclosed in Japanese Patent Application Laid-Open No. 64586/76, or react an organic metal compound with an orthosilicic ester, or react metallic magnesium, an orthosilicic ester and an organic halide with one another as disclosed in U.S. Pat. No. 4,220,554.
None of these methods has, however, been found useful for the manufacture of a carrier for a catalyst which is fully satisfactory in all aspects of particle properties, catalytic activity and stereoregularity.
The inventors of this invention have accomplished this invention as a result of their energetic research efforts to obtain a carrier which is composed of uniform particles having a large surface area, and which provides a polymer having high degrees of activity and stereoregularity for a catalyst for polymerization of olefins.